Phase Change Ink Containing Ethylene Vinyl Acetate

ABSTRACT

A phase change ink composition including an ink vehicle; an optional colorant; and ethylene vinyl acetate in an amount of from about 0.1 to about 10 percent by weight based on the total weight of the phase change ink composition.

TECHNICAL FIELD

Described herein are phase change ink compositions containing ethylenevinyl acetate having improved scratch and fold characteristics.

BACKGROUND

Disclosed herein is a phase change ink composition comprising a carrier;an optional colorant; and ethylene vinyl acetate in an amount of fromabout 0.5 to about 5 percent by weight based on the total weight of thephase change ink composition.

In general, phase change inks (sometimes referred to as “hot melt inks”)are in the solid phase at ambient temperature, but exist in the liquidphase at the elevated operating temperature of an ink jet printingdevice. At the jet operating temperature, droplets of liquid ink areejected from the printing device and, when the ink droplets contact thesurface of the recording substrate, either directly or via anintermediate heated transfer belt or drum, they quickly solidify to forma predetermined pattern of solidified ink drops. Phase change inks havealso been used in other printing technologies, such as gravure printing.

Phase change inks for color printing typically comprise a phase changeink carrier composition which is combined with a phase change inkcompatible colorant. In a specific embodiment, a series of colored phasechange inks can be formed by combining ink carrier compositions withcompatible subtractive primary colorants. The subtractive primarycolored phase change inks can comprise four component dyes, namely,cyan, magenta, yellow and black, although the inks are not limited tothese four colors. These subtractive primary colored inks can be formedby using a single dye or a mixture of dyes. For example, magenta can beobtained by using a mixture of Solvent Red Dyes or a composite black canbe obtained by mixing several dyes. U.S. Pat. No. 4,889,560, U.S. Pat.No. 4,889,761, and U.S. Pat. No. 5,372,852, the disclosures of each ofwhich are totally incorporated herein by reference, teach that thesubtractive primary colorants employed can comprise dyes from theclasses of Color Index (C.I.) Solvent Dyes, Disperse Dyes, modified Acidand Direct Dyes, and Basic Dyes.

The colorants can also include pigments, as disclosed in, for example,U.S. Pat. No. 5,221,335, the disclosure of which is totally incorporatedherein by reference.

Phase change inks have also been used for applications such as postalmarking, industrial marking, and labeling.

Phase change inks are desirable for ink jet printers because they remainin a solid phase at room temperature during shipping, long term storage,and the like. In addition, the problems associated with nozzle cloggingas a result of ink evaporation with liquid ink jet inks are largelyeliminated, thereby improving the reliability of the ink jet printing.Further, in phase change ink jet printers wherein the ink droplets areapplied directly onto the final recording substrate (for example, paper,transparency material, and the like), the droplets solidify immediatelyupon contact with the substrate, so that migration of ink along theprinting medium is prevented and dot quality is improved.

Compositions suitable for use as phase change ink carrier compositionsare known. Some representative examples of references disclosing suchmaterials include U.S. Pat. No. 3,653,932, U.S. Pat. No. 4,390,369, U.S.Pat. No. 4,484,948, U.S. Pat. No. 4,684,956, U.S. Pat. No. 4,851,045,U.S. Pat. No. 4,889,560, U.S. Pat. No. 5,006,170, U.S. Pat. No.5,151,120, U.S. Pat. No. 5,372,852, U.S. Pat. No. 5,496,879, EuropeanPatent Publication 0187352, European Patent Publication 0206286, GermanPatent Publication DE 4205636AL, German Patent Publication DE 4205713AL,and PCT Patent Application WO 94/04619, the disclosures of each of whichare totally incorporated herein by reference. Suitable carrier materialscan include paraffins, microcrystalline waxes, polyethylene waxes, esterwaxes, fatty acids and other waxy materials, fatty amide containingmaterials, sulfonamide materials, resinous materials made from differentnatural sources (tall oil rosins and rosin esters, for example), andmany synthetic resins, oligomers, polymers, and copolymers.

Ink jetting devices are known in the art, and thus extensive descriptionof such devices is not required herein. As described in U.S. Pat. No.6,547,380, incorporated herein by reference, ink jet printing systemsgenerally are of two types: continuous stream and drop-on-demand. Incontinuous stream ink jet systems, ink is emitted in a continuous streamunder pressure through at least one orifice or nozzle. The stream isperturbed, causing it to break up into droplets at a fixed distance fromthe orifice. At the break-up point, the droplets are charged inaccordance with digital data signals and passed through an electrostaticfield that adjusts the trajectory of each droplet in order to direct itto a gutter for recirculation or a specific location on a recordingmedium. In drop-on-demand systems, a droplet is expelled from an orificedirectly to a position on a recording medium in accordance with digitaldata signals. A droplet is not formed or expelled unless it is to beplaced on the recording medium.

There are at least three types of drop-on-demand ink jet systems. Onetype of drop-on-demand system is a piezoelectric device that has as itsmajor components an ink filled channel or passageway having a nozzle onone end and a piezoelectric transducer near the other end to producepressure pulses. Another type of drop-on-demand system is known asacoustic ink printing. As is known, an acoustic beam exerts a radiationpressure against objects upon which it impinges. Thus, when an acousticbeam impinges on a free surface (i.e., liquid/air interface) of a poolof liquid from beneath, the radiation pressure which it exerts againstthe surface of the pool may reach a sufficiently high level to releaseindividual droplets of liquid from the pool, despite the restrainingforce of surface tension. Focusing the beam on or near the surface ofthe pool intensifies the radiation pressure it exerts for a given amountof input power. Still another type of drop-on-demand system is known asthermal ink jet, or bubble jet, and produces high velocity droplets. Themajor components of this type of drop-on-demand system are an ink filledchannel having a nozzle on one end and a heat generating resistor nearthe nozzle. Printing signals representing digital information originatean electric current pulse in a resistive layer within each inkpassageway near the orifice or nozzle, causing the ink vehicle (usuallywater) in the immediate vicinity to vaporize almost instantaneously andcreate a bubble. The ink at the orifice is forced out as a propelleddroplet as the bubble expands.

In a typical design of a piezoelectric ink jet device utilizing phasechange inks printing directly on a substrate or on an intermediatetransfer member, such as the one described in U.S. Pat. No. 5,372,852,incorporated herein by reference, the image is applied by jettingappropriately colored inks during four to eighteen rotations(incremental movements) of a substrate (an image receiving member orintermediate transfer member) with respect to the ink jetting head,i.e., there is a small translation of the printhead with respect to thesubstrate in between each rotation. This approach simplifies theprinthead design, and the small movements ensure good dropletregistration. At the jet operating temperature, droplets of liquid inkare ejected from the printing device and, when the ink droplets contactthe surface of the recording substrate, either directly or via anintermediate heated transfer belt or drum, they quickly solidify to forma predetermined pattern of solidified ink drops.

Thermal ink jet processes are well known and are described, for example,in U.S. Pat. Nos. 4,601,777, 4,251,824, 4,410,899, 4,412,224 and4,532,530, the disclosures of each of which are hereby incorporatedherein.

Ink jet printing processes may employ inks that are solid at roomtemperature and liquid at elevated temperatures. Such inks may bereferred to as hot melt inks or phase change inks. For example, U.S.Pat. No. 4,490,731, which is hereby incorporated by reference herein,discloses an apparatus for dispensing solid ink for printing on asubstrate such as paper. In thermal ink jet printing processes employinghot melt inks, the solid ink is melted by the heater in the printingapparatus and utilized (i.e., jetted) as a liquid in a manner similar tothat of conventional thermal ink jet printing. Upon contact with theprinting substrate, the molten ink solidifies rapidly, enabling thecolorant to substantially remain on the surface of the substrate insteadof being carried into the substrate (for example, paper) by capillaryaction, thereby enabling higher print density than is generally obtainedwith liquid inks. Advantages of a phase change ink in ink jet printingare thus elimination of potential spillage of the ink during handling, awide range of print density and quality, minimal paper cockle ordistortion, and enablement of indefinite periods of nonprinting withoutthe danger of nozzle clogging, even without capping the nozzles.

Examples of the phase change inks herein are inks that include an inkvehicle that is solid at temperatures of about 23° C. to about 27° C.,for example room temperature, and specifically are solid at temperaturesbelow about 60° C. However, the inks change phase upon heating, and arein a molten state at jetting temperatures. Thus, the inks have aviscosity of from about 1 to about 20 centipoise (cp), for example fromabout 5 to about 15 cp or from about 8 to about 12 cp, at an elevatedtemperature suitable for ink jet printing, for example temperatures offrom about 60° C. to about 150° C.

In this regard, the inks herein may be either low energy inks or highenergy inks. Low energy inks are solid at a temperature below about 40°C. and have a viscosity of from about 1 to about 20 centipoise such asfrom about 5 to about 16 centipoise, for example from about 8 to about12 cp, at a jetting temperature of from about 60° C. to about 120° C.such as about 80° C. to about 115° C., for example from about 90° C. toabout 115° C. High energy inks are solid at a temperature below 40° C.and have a viscosity of from about 5 to about 16 centipoise at a jettingtemperature of from about 120° C. to about 180° C., for example from120° C. to about 160° C. or from about 125° C. to about 150° C.

Current solid ink formulations can employ a high content of polyethylenewax. Dye-based and pigmented solid inks based on polyethylene waxcarrier compositions can be relatively brittle and therefore can sufferfrom lack of scratch and fold resistance.

Currently available phase change ink compositions are suitable for theirintended purposes. However a need remains for improved phase changeinks. Further, a need remains for an improved pigmented and dye-basedphase change ink compositions. Further, a need remains for a phasechange ink having improved performance with respect to scratch and foldresistance while preserving the desired characteristics of phase changeink, particularly while preserving the desired characteristics ofpigmented solid inks, including Newtonian rheology, good filtrationproperties, thermal stability, and ink jetting robustness.

The appropriate components and process aspects of the each of theforegoing U.S. Patents and Patent Publications may be selected for thepresent disclosure in embodiments thereof. Further, throughout thisapplication, various publications, patents, and published patentapplications are referred to by an identifying citation. The disclosuresof the publications, patents, and published patent applicationsreferenced in this application are hereby incorporated by reference intothe present disclosure to more fully describe the state of the art towhich this invention pertains.

SUMMARY

Described is a phase change ink composition comprising an ink vehicle;an optional colorant; and ethylene vinyl acetate in an amount of fromabout 0.1 to about 10 percent by weight based on the total weight of thephase change ink composition.

Also described is a method for preparing a phase change ink compositioncomprising combining an ink vehicle; an optional colorant; and ethylenevinyl acetate in an amount of from about 0.1 to about 10 percent byweight based on the total weight of the phase change ink composition toproduce a phase change ink composition.

Also described is a method comprising incorporating into an ink jetprinting apparatus a phase change ink composition comprising an inkvehicle; an optional colorant; and ethylene vinyl acetate in an amountof from about 0.1 to about 10 percent by weight based on the totalweight of the phase change ink composition; melting the ink composition;and causing droplets of the melted ink to be ejected in an imagewisepattern onto a substrate.

Also described is an ink jet printer stick or pellet containing a phasechange ink composition comprising an ink vehicle; an optional colorant;and ethylene vinyl acetate in an amount of from about 0.1 to about 10percent by weight based on the total weight of the phase change inkcomposition.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a bar graph showing IQAF scratch for a comparative pigmentedcyan phase change ink and for pigmented cyan phase change ink inaccordance with the present disclosure.

FIG. 2 is a bar graph showing IQAF fold for a comparative pigmented cyanphase change ink and for pigmented cyan phase change ink in accordancewith the present disclosure and for pigmented cyan phase change ink inaccordance with the present disclosure.

FIG. 3 is a bar graph showing IQAF scratch for comparative pigmentedcyan phase change ink and for pigmented cyan phase change ink inaccordance with the present disclosure.

FIG. 4 is a bar graph showing IQAF fold for comparative pigmented cyanphase change ink and for pigmented cyan phase change ink in accordancewith the present disclosure.

FIG. 5 is a bar graph showing IQAF scratch for a comparative dye-basedcyan phase change ink and for dye-based cyan phase change ink inaccordance with the present disclosure.

FIG. 6 is a bar graph showing IQAF fold for a comparative dye-based cyanphase change ink and for dye-based cyan phase change ink in accordancewith the present disclosure.

DETAILED DESCRIPTION

In embodiments, ethylene vinyl acetate copolymers are employed in bothdye-based and pigmented solid inks in order to increase scratch and foldrobustness of the resulting prints.

Currently available phase change ink compositions are suitable for theirintended purposes. However a need remains for improved phase changeinks. In particular, the problem of lack of image robustness can stillexist for certain inks. The present inventors have found that the imagerobustness of solid ink can be substantially improved by incorporating asmall amount of ethylene vinyl acetate. “Image robustness” herein ismeant to include scratch and fold resistance. In embodiments, theaddition of from about 0.1 to about 10, or 0.5 to about 5, or from about3 to about 5 percent by weight ethylene vinyl acetate to pigmented solidink based on the total weight of the pigmented solid ink compositionsignificantly improves the performance of the ink with respect toscratch and fold resistance. For example, pigmented cyan ink printscratches almost 4 times less by incorporation into the pigmented inkformulation about 5 percent by weight ethylene vinyl acetate based onthe total weight of the pigmented ink formulation with the ethylenevinyl acetate containing about 13 percent vinyl acetate by weight basedon the total weight of the ethylene vinyl acetate.

Ethylene vinyl acetate is a copolymer of ethylene and vinyl acetate. Theweight percent of vinyl acetate in ethylene vinyl acetate typicallyvaries from about 6 to about 40 percent vinyl acetate, where the weightpercentage of ethylene in the polymer molecule exceeds that of the vinylacetate. The vinyl acetate content and the molecular weight rangeinfluence hot melt rheology and particularly adhesive properties. Thehigher the ethylene content, the better the specific adhesion tonon-polar substrates, such as polyolefins. The polymers higher in vinylacetate show improved adhesion to polar substrates, such as paper. Inembodiments herein, ethylene vinyl acetate having a higher level ofvinyl acetate is selected. Lower molecular weight polymers yieldlower-melt viscosity solid inks that are easier to process and apply.

Ethylene vinyl acetate as employed in the phase change ink compositionsherein provides the softness and flexibility of elastomeric materialsand the processing ability of thermoplastics. Further, ethylene vinylacetate imparts good clarity, barrier properties, low-temperaturetoughness, stress-crack resistance, hot-melt adhesive, heat-sealingproperties, and ultra-violet (UV) radiation resistance.

Ethylene vinyl acetate and hydrocarbon waxes are selected in embodimentsherein to complement one another in use in the phase change inkcompositions. Each of the ethylene vinyl acetate and hydrocarbon waxcomponents has a certain set of properties that is selected to optimizethe performance of the overall phase change ink composition. Hydrocarbonwax is relatively low priced, has low viscosity, good barrier propertiesto water vapor, and a very fast solidification time. Ethylene vinylacetate has a high cohesive strength and good adhesion to paper, andenables the wax to maintain its water barrier properties.

Random ethylene vinyl acetate copolymers can have the followingstructure

wherein n is an integer, and wherein, in embodiments, n is an integerfrom about 10 to about 220, and where m is an integer, and wherein, inembodiments, m is an integer from about 1 to about 40.

Examples of ethylene vinyl acetate include N8036, N8038F, N8038, N8045,MV1055, SV1055 and TV1055 available from Kamdar Plastics. Other examplesof ethylene vinyl acetate available from Honeywell International Inc.include A-C® 400, A-C® 430, A-C® 405M, A-C® 405S, A-C® 405T, A-C® 415and A-C® 430.

Still other examples of ethylene vinyl acetate are Nipoflex® 625,Nipoflex® 630, Nipoflex® 631, Nipoflex® 633, Nipoflex® 634, Nipoflex®Nipoflex® 680, Nipoflex® 681, Nipoflex® 710, Nipoflex® 720, Nipoflex®722 and Nipoflex® 750 available from Tosoh Corporation.

The ethylene vinyl acetate can be present in the phase change inkcomposition herein at any suitable or desired amount. In embodiments,ethylene vinyl acetate is present in the phase change ink composition inan amount of from about 0.1 to about 10, or from about 0.5 to about 10,or from about 0.5 to about 5, or from about 1 to about 7, or from about3 to about 5, or from about 4 to about 5 weight percent based on thetotal weight of the phase change ink composition. In certainembodiments, ethylene vinyl acetate is selected in an amount of fromabout 0.5 to about 5, or from about 1.5 to about 5, or less than about 5percent by weight based on the total weight of the phase change inkcomposition.

In embodiments, ethylene vinyl acetates having different levels of vinylacetate content were formulated in solid ink at loadings of from about1.5 to about 5% by weight based on the total weight of the solid inkcomposition. The prepared inks were filtered and characterized bysettling stability and rheology. All inks retained the expecteddye-based and pigmented solid ink characteristics. The inks weresuccessfully jetted and tested for scratch and fold.

In embodiments, ethylene vinyl acetate herein has a vinyl acetatecontent of from about 1 to about 40 percent, of from about 5 to about 30percent, or from about 5 to about 16 percent, based on the total weightof the ethylene vinyl acetate.

In certain embodiments, the ethylene vinyl acetate is present in anamount of from about 0.5 to about 5 percent by weight, or from about 1.5to about 5 percent by weight based on the total weight of the phasechange ink composition and the ethylene vinyl acetate has a vinylacetate content of about from about 5 to about 13 percent vinyl acetatebased on the total weight of the ethylene vinyl acetate.

In other embodiments, the ethylene vinyl acetate is present in the phasechange ink composition in an amount of about 0.5 percent by weight,based on the total weight of the phase change ink composition, and theethylene vinyl acetate has a vinyl acetate content of about 25 to about30 percent vinyl acetate based on the total weight of the ethylene vinylacetate.

In embodiments, the ethylene vinyl acetate is selected for specificproperties that enable the ethylene vinyl acetate materials to work as acomponent in the phase change ink. In certain embodiments, the ethylenevinyl acetate herein is selected to have a certain molecular weightaverage, a certain melting point, a certain freezing point, and acertain viscosity which enable or enhance performance in the phasechange ink, such as good phase change performance.

In embodiments, the ethylene vinyl acetate selected for the phase changeink herein has a molecular weight average of from about 30,000 to about150,000, or from about 40,000 to about 120,000, or from about 50,000 toabout 100,000 Daltons.

In embodiments, the ethylene vinyl acetate selected for the phase changeink herein has a melting point of from about 45 to about 120, or fromabout 55 to about 110, or from about 80 to about 100° C.

In embodiments, the ethylene vinyl acetate selected for the phase changeink herein has a freezing point of from about 25 to about 100, or fromabout 35 to about 90, or from about 60 to about 80° C.

In embodiments, the ethylene vinyl acetate selected for the phase changeink herein has a viscosity of from about 150 to about 2,000, or fromabout 300 to about 15,000, or from about 400 to about 1,000 cps at 140°C.

Selected properties, provided by Honeywell International Inc., ofselected ethylene vinyl acetate copolymers are provided in Table 1.

TABLE 1 Copolymers/ Hard- Ethylene- ness Density Viscosity Vinyl Vinyl(ASTM g/cc (ASTM @ 140° C. Product Acetate Acetate D-5) D-1505) cps Form% A-C ® 400A 9.5 0.92 595 Powder 12-16 A-C ® 400M 4-8 0.92 600 Prill7.5-9.4 A-C ® 405T 3-7 0.92 600 Prill   5-7.4

In embodiments, an ink herein is prepared having a viscosity of about 10to about 16 centipoise at 110° C.

The phase change ink compositions herein can include any suitable inkvehicle or carrier such as paraffins, microcrystalline waxes,polyethylene waxes, ester waxes, amides, fatty acids and other waxymaterials, fatty amide containing materials, sulfonamide materials,resinous materials made from different natural sources (tall oil rosinsand rosin esters, for example), and many synthetic resins, oligomers,polymers, and copolymers.

In embodiments, the phase change ink compositions herein include a phasechange ink vehicle or carrier, in embodiments, a wax, in embodiments apolyalkylene wax. In further embodiments, the wax is a polymethylenewax, a polyethylene wax, or a mixture of combination thereof.

In certain embodiments, the phase change ink compositions herein includea biodegradable and compostable wax. In embodiments, the biodegradableand compostable wax is a biodegradable and compostable polyethylene waxsuch as Accumelt® 72, IGI 1266A, and the like, from International Group,Inc. Compostable wax as used herein is a compostable material based onASTM D6400-04 (ASTM Publications), which is hereby incorporated byreference herein in its entirety, which recites a compostable plastic isa plastic that undergoes degradation by biological process duringcompositing to yield carbon dioxide, water, inorganic compounds, andbiomass at a rate consistent with other known compostable materials andleaves substantially no visually distinguishable or toxic residues.

In embodiments, the phase change ink compositions herein furthercomprises a low melting wax. In embodiments, the low melting wax is apolyalkylene wax, a functional wax, or a combination thereof. The term“functional wax” is known to one of skill in the art and can mean hereinany suitable functional wax, in embodiments, including, but not limitedto, a wax with polar groups, for example, alcohols, amides, esters,urethanes, etc. As used herein, the term “low melting wax” includes anysuitable low melting wax, including, in embodiments, a wax having amelting point of less than about 120° C.

Examples of suitable amides include, for example, diamides, triamides,tetra-amides, cyclic amides and the like. Suitable triamides include,for example, those disclosed in U.S. Pat. No. 6,860,930, the entiredisclosure of which is incorporated herein by reference. Suitable otheramides, such as fatty amides including monoamides, tetra-amides, andmixtures thereof, are disclosed in, for example, U.S. Pat. Nos.4,889,560, 4,889,761, 5,194,638, 4,830,671, 6,174,937, 5,372,852,5,597,856, and 6,174,937, and British Patent No. GB 2 238 792, theentire disclosures of each are incorporated herein by reference.

The ink vehicle or carrier can be present in the phase change inkcomposition in any suitable or desired amount. In embodiments, the waxis present in the phase change ink composition in an amount of fromabout 25 percent to about 65 percent by weight based on the total weightof the phase change ink composition. In embodiments, the wax is a lowmelting wax present in the phase change ink composition in an amount offrom about 25% to less than about 65% by weight based on the totalweight of the ink carrier.

Other suitable carrier materials that can be used in the phase changeink composition include isocyanate-derived resins and waxes, such asurethane isocyanate-derived materials, urea isocyanate-derivedmaterials, urethane/urea isocyanate-derived materials, mixtures thereof,and the like. Further information on isocyanate-derived carriermaterials is disclosed in, for example, U.S. Pat. Nos. 5,750,604,5,780,528, 5,782,966, 5,783,658, 5,827,918, 5,830,942, 5,919,839,6,255,432, and 6,309,453, British Patents Nos. GB 2 294 939, GB 2 305928, GB 2 305 670, and GB 2 290 793, and PCT Publications WO 94/14902,WO 97/12003, WO 97/13816, WO 96/14364, WO 97/33943, and WO 95/04760, theentire disclosures of each of which are incorporated herein byreference.

In embodiments, the ink vehicle comprises a mixture of one or moreamides and one or more isocyanate-derived materials.

Further examples of suitable ink vehicles include ethylene/propylenecopolymers, such as those available from Baker Petrolite. Commercialexamples of such copolymers include, for example, Petrolite CP-7(Mn=650), Petrolite CP-11 (Mn=1,100, Petrolite CP-12 (Mn=1,200) and thelike. The copolymers may have, for example, a melting point of fromabout 70° C. to about 150° C., such as from about 80° C. to about 130°C. or from about 90° C. to about 120° C. and a molecular weight range(Mn) of from about 500 to about 4,000.

Another type of ink vehicle may be n-paraffinic, branched paraffinic,and/or naphthenic hydrocarbons, typically with from about 5 to about100, such as from about 20 to about 80 or from about 30 to about 60carbon atoms, generally prepared by the refinement of naturallyoccurring hydrocarbons, such as BE SQUARE 185 and BE SQUARE 195, withmolecular weights (Mn) of from about 100 to about 5,000, such as fromabout 250 to about 1,000 or from about 500 to about 800, for examplesuch as available from Baker Petrolite.

Highly branched hydrocarbons, typically prepared by olefinpolymerization, such as the VYBAR materials available from BakerPetrolite, including VYBAR 253 (Mn=520), VYBAR 5013 (Mn=420), and thelike, may also be used. In addition, the ink vehicle may be anethoxylated alcohol, such as available from Baker Petrolite and of thegeneral formula

wherein x is an integer of from about 1 to about 50, such as from about5 to about 40 or from about 11 to about 24 and y is an integer of fromabout 1 to about 70, such as from about 1 to about 50 or from about 1 toabout 40. The materials may have a melting point of from about 60° C. toabout 150° C., such as from about 70° C. to about 120° C. or from about80° C. to about 110° C. and a molecular weight (Mn) range of from about100 to about 5,000, such as from about 500 to about 3,000 or from about500 to about 2,500. Commercial examples include UNITHOX 420 (Mn=560),UNITHOX 450 (Mn=900), UNITHOX 480 (Mn=2,250), UNITHOX 520 (Mn=700),UNITHOX 550 (Mn=1,100), UNITHOX 720 (Mn=875), UNITHOX 750 (Mn=1,400),and the like.

As an additional example, the ink vehicle may be made of fatty amides,such as monoamides, tetra-amides, mixtures thereof, and the like, forexample such as described in U.S. Pat. No. 6,858,070, which is herebyincorporated herein by reference. In embodiments, the ink vehiclecomprises a monoamide, a triamide, or a mixture thereof. Suitablemonoamides may have a melting point of at least about 50° C., forexample from about 50° C. to about 150° C., although the melting pointcan be outside these ranges. Specific examples of suitable monoamidesinclude, for example, primary monoamides and secondary monoamides.Stearamide, such as KEMAMIDE® S available from Chemtura Corporation andCRODAMIDE® S available from Croda, behenamide/arachidamide, such asKEMAMIDE® B available from Chemtura Corporation and CRODAMIDE® BRavailable from Croda, oleamide, such as KEMAMIDE® U available fromChemtura Corporation and CRODAMIDE® OR available from Croda, technicalgrade oleamide, such as KEMAMIDE® 0 available from Chemtura Corporation,CRODAMIDE® 0 available from Croda, and UNISLIP® 1753 available fromUniqema, and erucamide such as KEMAMIDE® E available from ChemturaCorporation and CRODAMIDE® ER available from Croda, are some examples ofsuitable primary amides. Behenyl behenamide, such as KEMAMIDE® EX666available from Chemtura Corporation, stearyl stearamide, such asKEMAMIDE® S-180 and KEMAMIDE® EX-672 available from ChemturaCorporation, stearyl erucamide, such as KEMAMIDE® E-180 available fromChemtura Corporation and CRODAMIDE® 212 available from Croda, erucylerucamide, such as KEMAMIDE® E-221 available from Chemtura Corporation,oleyl palmitamide, such as KEMAMIDE® P-181 available from ChemturaCorporation and CRODAMIDE® 203 available from Croda, and erucylstearamide, such as KEMAMIDE® S-221 available from Chemtura Corporation,are some examples of suitable secondary amides. Additional suitableamide materials include KEMAMIDE® W40 (N,N′-ethylenebisstearamide),KEMAMIDE® P181 (oleyl palmitamide), KEMAMID®E W45(N,N′-ethylenebisstearamide), and KEMAMIDE® W20(N,N′-ethylenebisoleamide).

High molecular weight linear alcohols, such as those available fromBaker Petrolite and of the general formula

wherein x is an integer of from about 1 to about 50, such as from about5 to about 35 or from about 11 to about 23, may also be used as the inkvehicle. These materials may have a melting point of from about 50° C.to about 150° C., such as from about 70° C. to about 120° C. or fromabout 75° C. to about 110° C., and a molecular weight (Mn) range of fromabout 100 to about 5,000, such as from about 200 to about 2,500 or fromabout 300 to about 1,500. Commercial examples include the UNILIN®materials such as UNILIN® 425 (Mn=460), UNILIN® 550 (Mn=550), UNILIN®700 (Mn=700), and distilled alcohols, the viscosity of which at thejetting temperature in one embodiment can be from about 5 to about 50%higher than the non-distilled alcohol.

A still further example includes hydrocarbon-based waxes, such as thehomopolymers of polyethylene available from Baker Petrolite and of thegeneral formula

wherein x is an integer of from about 1 to about 200, such as from about5 to about 150 or from about 12 to about 105. These materials may have amelting point of from about 60° C. to about 150° C., such as from about70° C. to about 140° C. or from about 80° C. to about 130° C. and amolecular weight (Mn) of from about 100 to about 5,000, such as fromabout 200 to about 4,000 or from about 400 to about 3,000. Example waxesinclude PW400 (Mn about 400), distilled PW400, in one embodiment havinga viscosity of about 10% to about 100% higher than the viscosity of theundistilled POLYWAX® 400 at about 110° C., POLYWAX 500 (Mn about 500),distilled POLYWAX® 500, in one embodiment having a viscosity of about10% to about 100% higher than the viscosity of the undistilled POLYWAX®500 at about 110° C., POLYWAX 655 (Mn about 655), distilled POLYWAX®655, in one embodiment having a viscosity of about 10% to about 50%lower than the viscosity of the undistilled POLYWAX® 655 at about 110°C., and in yet another embodiment having a viscosity of about 10% toabout 50% higher than the viscosity of the undistilled POLYWAX® 655 atabout 110° C. POLYWAX 850 (Mn about 850), POLYWAX 1000 (Mn about 1,000),and the like.

Another example includes modified maleic anhydride hydrocarbon adductsof polyolefins prepared by graft copolymerization, such as thoseavailable from Baker Petrolite and of the general formulas

wherein R is an alkyl group with from about 1 to about 50, such as fromabout 5 to about 35 or from about 6 to about 28 carbon atoms, R′ is anethyl group, a propyl group, an isopropyl group, a butyl group, anisobutyl group, or an alkyl group with from about 5 to about 500, suchas from about 10 to about 300 or from about 20 to about 200 carbonatoms, x is an integer of from about 9 to about 13, and y is an integerof from about 1 to about 50, such as from about 5 to about 25 or fromabout 9 to about 13, and having melting points of from about 50° C. toabout 150° C., such as from about 60° C. to about 120° C. or from about70° C. to about 100° C.; and those available from Baker Petrolite and ofthe general formula

wherein R₁ and R₃ are hydrocarbon groups and R₂ is either of one of thegeneral formulas

or a mixture thereof, wherein R′ is an isopropyl group, which materialsmay have melting points of from about 70° C. to about 150° C., such asfrom about 80° C. to about 130° C. or from about 90° C. to about 125°C., with examples of modified maleic anhydride copolymers includingCERAMER 67 (Mn=655, Mw/Mn=1.1), CERAMER 1608 (Mn=700, Mw/Mn=1.7), andthe like.

Additional examples of suitable ink vehicles for the phase change inksinclude rosin esters; polyamides; dimer acid amides; fatty acid amides,including ARAMID C; epoxy resins, such as EPOTUF 37001, available fromRiechold Chemical Company; fluid paraffin waxes; fluid microcrystallinewaxes; Fischer-Tropsch waxes; polyvinyl alcohol resins; polyols;cellulose esters; cellulose ethers; polyvinyl pyridine resins; fattyacids; fatty acid esters; poly sulfonamides, including KETJENFLEX MH andKETJENFLEX MS80; benzoate esters, such as BENZOFLEX 5552, available fromVelsicol Chemical Company; phthalate plasticizers; citrate plasticizers;maleate plasticizers; sulfones, such as diphenyl sulfone, n-decylsulfone, n-arnyl sulfone, chlorophenyl methyl sulfone; polyvinylpyrrolidinone copolymers; polyvinyl pyrrolidone/polyvinyl acetatecopolymers; novolac resins, such as DUREZ 12 686, available fromOccidental Chemical Company; and natural product waxes, such as beeswax,monton wax, candelilla wax, GILSONITE (American Gilsonite Company), andthe like; mixtures of linear primary alcohols with linear long chainamides or fatty acid amides, such as those with from about 6 to about 24carbon atoms, including PARICIN 9 (propylene glycolmonohydroxystearate), PARICIN 13 (glycerol monohydroxystearate), PARICIN15 (ethylene glycol monohydroxystearate), PARICIN 220(N(2-hydroxyethyl)-12-hydroxystearamide), PARICIN 285(N,N′-ethylene-bis-12-hydroxystearamide), FLEXRICIN 185(N,N′-ethylene-bis-ricinoleamide), and the like. Further, linear longchain sulfones with from about 4 to about 16 carbon atoms, such asn-propyl sulfone, n-pentyl sulfone, n-hexyl sulfone, n-heptyl sulfone,n-octyl sulfone, n-nonyl sulfone, n-decyl sulfone, n-undecyl sulfone,n-dodecyl sulfone, n-tridecyl sulfone, n-tetradecyl sulfone,n-pentadecyl sulfone, n-hexadecyl sulfone, and the like, are suitableink vehicle materials.

In embodiments, the ink vehicle comprises (a) stearyl stearamide, (b) atriamide, or (c) mixtures thereof.

In addition, the ink vehicles described in U.S. Pat. No. 6,906,118,which is incorporated herein by reference, may also be used. The inkvehicle may contain a branched triamide such as those described in U.S.Pat. No. 6,860,930, the disclosure of which is also incorporated byreference herein,

wherein n has an average value of from about 34 equal to or less than40, where x, y and z can each be zero or an integer, and wherein the sumof x, y, and z is from about 5 and equal to or less than 6.

Optionally, a plasticizer, which can be either a solid or liquidplasticizer, such as benzyl phthalates, triaryl phosphate esters,pentaerythritol tetrabenzoate, dialkyl adipate, dialkyl phthalates,dialkyl sebacate, alkyl benzyl phthalates, ethylene glycol monostearate,glycerol monostearate, propylene glycol monostearate, dicyclohexylphthalate, diphenyl isophthalate, triphenyl phosphate, dimethylisophthalate, and mixtures thereof, or the like can also be included inthe ink carrier. The plasticizer is present in the ink carrier in anydesired or effective amount, such as from about 0.05% by weight of theink carrier. Examples of suitable plasticizers include SANTICIZER® 278,SANTICIZER® 154, SANTICIZER®160, SANTICIZER® 261 (commercially availablefrom Monsanto), and the like or mixtures thereof.

An antioxidant such as a hindered amine antioxidant can optionally bepresent in the ink in any desired or effective amount, such as fromabout 0.001 percent to about 0.50 percent by weight of the total inkcomposition.

Examples of suitable hindered amine antioxidants include those ofgeneral formula

wherein R₁ and R₂ each, independently of the other, can be a hydrogenatom or an alkyl group, including linear, branched, saturated,unsaturated, cyclic, substituted, and unsubstituted alkyl groups, andwherein hetero atoms, such as oxygen, nitrogen, sulfur, silicon,phosphorus, boron, either may or may not be present in the alkyl group,in one embodiment with at least 1 carbon atom, if substituted,substitutions can be alkyl or phenyl.

Specific examples of suitable hindered amine antioxidants include thefollowing antioxidants commercially available from Crompton; NAUGUARD®445 where R₁═R₂=C(CH₃)₂Ph, NAUGUARD® 635 where R₁═R₂═—CH(CH₃)Ph,NAUGUARD® PS-30 where R₁═C₄ or C₈, R₂═C₄ or C₈ and the like.

A hindered phenol antioxidant can also be provided. In one embodimentthe hindered phenol is present in a relatively high concentration. Ahigh concentration of hindered phenol antioxidant maximizes long termthermal stability by delaying the onset of the oxidation itself. Thehindered phenol antioxidant is present in the ink in any desired oreffective amount, in embodiments from about 0.01% to about 4.0% byweight of the total ink composition. Specific examples of suitablehindered phenol antioxidants include ETHANOX® 330, ETHANOX® 310,ETHANOX® 314, ETHANOX® 376 (commercially available from Albemarle) andthe like. Also commercially available from Ciba Specialty Chemicals areIRGANOX® 1010, IRGANOX® 1035, IRGANOX®1076, IRGANOX® 1330 and the like.Mixtures of two or more of these hindered phenol antioxidants can alsobe employed.

A rosin ester resin, mixtures thereof, or the like can also be includedin the phase change ink composition. The rosin ester resin is present inany desired or effective amount, in embodiments from 0.5% to about 20%by weight of the total ink composition. Examples of suitable rosin esterresins include Pinecrystal KE-100 (commercially available from ArakawaChemical Industries), and the like.

The phase change ink composition can include ink carrier comprising waxand other optional carrier components in any desired or effectiveamount, in one embodiment in an amount of at least about 50% by weightof the ink, in another embodiment of at least about 70% by weight of theink, and in yet another embodiment of at least about 90% by weight ofthe ink, and in one embodiment equal to or less than about 99% by weightof the ink, in another embodiment equal to or less than about 98% byweight of the ink, and in yet another embodiment equal to or less thanabout 95% by weight of the ink, although the amount can be outside ofthese ranges. In certain embodiments, in an amount of from about 25% toabout 65% by total weight of the phase change ink composition.

In one specific embodiment, the ink carrier has a melting point of lessthan about 110° C., and in another embodiment of less than about 100°C., although the melting point of the ink carrier can be outside ofthese ranges.

The phase change ink compositions also contain an optional colorant. Thecolorant can be any suitable or desired colorant including dyes,pigments, and mixtures and combinations thereof. In specificembodiments, the colorant is a pigment. In other embodiments, thecolorant is a dye. In certain embodiments, the colorant is a cyanpigment. In certain other embodiments, the colorant is a cyan dye.

The colorant is present in the phase change ink in any desired oreffective amount to obtain the desired color or hue, in embodiments fromabout 0.1 to about 15 percent by weight based on the total weight of thephase change ink composition.

The phase change ink compositions disclosed herein in one embodimenthave melting points in one embodiment equal to or less than about 130°C., in another embodiment equal to or less than about 120° C., in afurther embodiment equal to or less than about 110° C., and in stillanother embodiment equal to or less than about 100° C., although themelting point can be outside of these ranges.

The phase change ink compositions herein generally have meltviscosities, at the jetting temperature which can be equal to or lessthan about 145° C., in one embodiment equal to or less than about 130°C., and in another embodiment equal to or less than about 120° C., in afurther embodiment equal to or less than about 110° C., and in yetanother embodiment equal to or less than about 80° C., although thejetting temperature can be outside of these ranges, which are in oneembodiment equal to or less than about 30 centipoise (cps), in anotherembodiment equal to or less than about 25 cps, and in yet a furtherembodiment equal to or less than about 20 cps, and in another embodimentno less than about 2 cps, in a further embodiment no less than about 3cps, and in yet a further embodiment no less than about 4 cps, althoughthe melt viscosity can be outside of these ranges.

In certain embodiments, the phase change ink composition herein has ajetting temperature of from about 100° C. to about 130° C.

In embodiments, the phase change ink composition herein has a viscosityof about 10 to about 16 centipoise at 110° C.

The phase ink compositions of the present disclosure can be prepared byany desired or suitable method. In embodiments, a method for preparing aphase change ink composition comprises combining a wax; an optionalcolorant; and ethylene vinyl acetate to produce a phase change inkcomposition. For example, the ink ingredients can be mixed together,followed by heating, to a temperature of at least about 100° C. to nomore than about 140° C., although the temperature can be outside of thisrange, and stirring until a homogeneous ink composition is obtained,followed by cooling the ink to ambient temperature (typically from about20 to about 25° C.). The inks of the present disclosure are solid atambient temperature. In a specific embodiment, during the formationprocess, the inks in their molten state are poured into molds and thenallowed to cool and solidify to form ink sticks.

The inks disclosed herein can be employed in apparatus for directprinting ink jet processes and in indirect (offset) printing ink jetapplications. Another embodiment is directed to a process whichcomprises incorporating an ink as disclosed herein into an ink jetprinting apparatus, melting the ink, and causing droplets of the meltedink to be ejected in an imagewise pattern onto a recording substrate. Adirect printing process is also disclosed in, for example, U.S. Pat. No.5,195,430, the disclosure of which is totally incorporated herein byreference. The inks prepared as disclosed herein can be employed inapparatus for indirect (offset) printing ink jet applications. Anotherembodiment is directed to a process which comprises incorporating an inkprepared as disclosed herein into an ink jet printing apparatus, meltingthe ink, causing droplets of the melted ink to be ejected in animagewise pattern onto an intermediate transfer member, and transferringthe ink in the imagewise pattern from the intermediate transfer memberto a final recording substrate. In a specific embodiment, theintermediate transfer member is heated to a temperature above that ofthe final recording sheet and below that of the melted ink in theprinting apparatus. An offset or indirect printing process is alsodisclosed in, for example, U.S. Pat. No. 5,389,958, the disclosure ofwhich is totally incorporated herein by reference. In one specificembodiment, the printing apparatus employs a piezoelectric printingprocess wherein droplets of the ink are caused to be ejected inimagewise pattern by oscillations of piezoelectric vibrating elements.

Any suitable substrate or recording sheet can be employed, includingplain papers such as XEROX® 4024 papers, XEROX® Image Series papers,Courtland 4024 DP paper, ruled notebook paper, bond paper, silica coatedpapers such as Sharp Company silica coated paper, JuJo paper, HammermillLaserprint Paper, and the like, transparency materials, fabrics, textileproducts, plastics, polymeric films, inorganic substrates such as metalsand wood, and the like.

EXAMPLES

The following Examples are being submitted to further define variousspecies of the present disclosure. These Examples are intended to beillustrative only and are not intended to limit the scope of the presentdisclosure. Also, parts and percentages are by weight unless otherwiseindicated.

Ethylene vinyl acetate copolymers with different levels of vinyl acetatewere obtained from Honeywell International Inc. The dispersant used wasprepared as described in Example 1 of U.S. Pat. No. 7,973,186, which ishereby incorporated by reference herein in its entirety. The componentsof the solid ink are presented in Table 2 below:

TABLE 2 Ink Base Component Details Accumelt ® R3910 A fractionatedpolymethylene wax available from The International Group, Inc. Triamidewax Triamide wax Xerox U.S. Pat. No. 6,860,930 KEMAMIDE ® S-180 Stearylstearamide KE-100 triglycerides of hydrogenated abietic acid Urethaneresin urethane resin, Xerox U.S. Pat. No. 6,309,453 Naugard ® 445Antioxidant

Triamide wax as prepared in Example 1 of U.S. Pat. No. 6,860,930, whichis hereby incorporated by reference herein in its entirety.

KEMAMIDE® S-180, stearyl stearamide available from Chemtura Corporation.

KE-100, triglycerides of hydrogenated abietic acid, available fromArakawa Chemical Industries.

Urethane resin as prepared in Example 4 of U.S. Pat. No. 6,309,453,which is hereby incorporated by reference herein in its entirety.

Naugard® 445, aromatic amine antioxidant available from ChemturaCorporation.

Cyan dye as prepared in Example VII of U.S. Pat. No. 6,476,219, which ishereby incorporated by reference herein in its entirety, was prepared asfollows.

A mixture of 4-(3-pentadecyl) phenoxyphthalonitrile (25.8 grams, 0.060mole), copper(II) acetate dehydrate (3.0 grams, 0.015 mole), andammonium acetate (9.2 grams, 0.12 mole) in 100 milliliters of NMP wasstirred and heated to 120° C. Slow gas evolution was observed, and after5 minutes a deep, dark blue color developed. After 30 minutes as 120° C.the reaction mixture was heated to 180° C. for 1 hour. NMP (50milliliters) was then added and the mixture was stirred and reheated to180° C., followed by cooling with stiffing to room temperature. Theproduct was then filtered and the solid was washed in the filter funnelwith 2×100 milliliter portion of DMF. It was then stiffed in 200milliliters of acetone at 50° C. and subsequently filtered. This acetonetreatment was repeated, and the solid was dried at 60° C. overnight togive the product as a coarse powder (19.9 grams, 74 percent). Thespectral strength of this material was 1.27×10⁵ A*ml/g, which isindicative of high (i.e. about 98 percent) purity.

Comparative Example 1 Standard Cyan Pigmented Solid Ink Formulation

Preparation of pigment concentrate. Cyan concentrates containing 15weight percent pigment, 12 weight percent dispersant prepared asdescribed in Example 1 of U.S. Pat. No. 7,973,186, 3.75 weight percentSunflo® SFD-B 124 (a derivatized sulfonated copper phthalocyanine,available from Sun Chemical) as synergist, and 69.25 weight percentKEMAMIDE® S-180 were processed in a Hockmeyer Equipment corporationmixer for 4 hours.

Preparation of solid ink containing pigment concentrate. A 12 gramsample of the concentrate obtained from the Hockmeyer mixer was placedinto a pre-heated vessel with pre-heated stiffer bar and allowed to stirfor 10 minutes. To this were slowly added, having already been meltedand thoroughly mixed at 120° C., 52.34 parts (52.34 grams) Accumelt®R3910, 12.52 parts (12.52 grams) triamide wax, 12.52 parts (12.52 grams)KE-100 resin, 1.18 parts (1.18 grams) urethane resin, 9.13 parts (9.13grams) KEMAMIDE® S-180, and 0.31 parts (0.31 grams) Naugard® 445. Theresultant ink was stirred for 2 hours at 120° C. The resultant ink wasfiltered through a 5 μm stainless steel mesh.

Example 2

Pigmented Cyan Ink. A pigmented cyan ink was prepared having theconcentrate and ink formulation in Comparative Example 1 but with theaddition of 3.0 weight percent ethylene vinyl acetate containing 13weight percent vinyl acetate (A-C 400A) added to the ink with stiffingto the molten ink. The resultant mixture was filtered through a 5 μmstainless steel mesh.

Example 3

Pigmented Cyan Ink. A pigmented cyan ink was prepared having theconcentrate and ink formulation in Comparative Example 1 but with theaddition of 3.0 weight percent ethylene vinyl acetate containing 6weight percent vinyl acetate (A-C® 405T) added to the ink with stiffingto the molten ink. The resultant mixture was filtered through a 5 μmstainless steel mesh.

Example 4

Pigmented Cyan Ink. A pigmented cyan ink was prepared having theconcentrate and ink formulation in Comparative Example 1 but with theaddition of 4.5 weight percent A-C® 400A added to the ink with stirringto the molten ink. The resultant mixture was filtered through a 5 μmstainless steel mesh.

Example 5

Pigmented Cyan Ink. A pigmented cyan ink was prepared having theconcentrate and ink formulation in Comparative Example 1 but with theaddition of 4.5 weight percent A-C® 405T added to the ink with stirringto the molten ink. The resultant mixture was filtered through a 5 μmstainless steel mesh.

Example 6

The concentrate formulation of Example 1 was prepared. 12 grams of theconcentrate of Comparative Example 1 was placed into a pre-heated vesselwith pre-heated stirrer bar and allowed to stir for 10 minutes. To thiswere slowly added, having already been melted and thoroughly mixed at120° C., 51.84 parts Accumelt® R3910, 12.52 parts (12.52 grams) triamidewax, 10.52 parts (10.52 grams) KE-100 resin, 1.18 parts (1.18 grams)urethane resin, 6.63 parts (6.63 grams) KEMAMIDE® S180, 0.31 parts (0.31grams) Naugard® 445, and 5.0 parts (5.0 percent) A-C® 400A. Theresultant ink was stirred for 2 hours at 120° C. and then filteredthrough a 5 μm stainless steel mesh.

Comparative Example 7

Dye-based Cyan Ink. A molten and thoroughly mixed blend consisting of52.44 (52.44 grams) parts Accumelt® R3910, 13.32 parts (13.32 grams)triamide wax (triamide wax described in Example 1 of U.S. Pat. No.6,860,930), 13.32 parts KE-100 resin, 14.89 parts (14.89 grams)KEMAMIDE® S180, 2.31 parts (2.31 grams) urethane resin, and 0.21 parts(0.21 grams) Naugard® 445 were placed into a 600 milliliter beaker ontop of a hot plate and allowed to stir for 1 hour at 105° C. To thiswere slowly added, 3.51 parts (3.51 grams) Blue Dye prepared asdescribed in Example VII of U.S. Pat. No. 6,476,219. The resultant inkwas stirred for 2.5 hours at 120° C. and then was filtered through a 5μm stainless steel mesh and 1 μm paper filter, respectively.

Example 8

Dye-based Cyan Ink. A dye-based cyan ink was prepared having theconcentrate and ink formulation in Comparative Example 7 but with theaddition of 1.5 percent of A-C® 400A added to the ink with stirring tothe molten ink. The resultant mixture was filtered through a 5 μmstainless steel mesh.

Example 9

Dye-based Cyan Ink. A dye-based cyan ink was prepared having theconcentrate and ink formulation in Comparative Example 7 but with theaddition of 5 percent of A-C® 405T added to the ink with stirring to themolten ink. The resultant mixture was filtered through a 5 μm stainlesssteel mesh.

The rheological properties of the inks were determined at 110° C. usinga 50 millimeter cone and plate geometry on a RFS-III rheometer, obtainedfrom Rheometrics Corporation, now TA Instruments, Inc. The shear rateviscosities at two different shear rates (from a shear rate sweep of 1to approximately 251.2 (s⁻¹) were compared. Newtonian behavior isrealized when the difference of the viscosities at each of thesecomparative shear rates, such as 1 and 100 s⁻¹ are minimized, such asbeing less than 1 cP, such as being less than 0.5 cP or zero. Therheology results indicated that the inks of the present disclosure,which incorporated ethylene vinyl acetate with different levels of vinylacetate, displayed Newtonian behavior as can be seen in Table 3.

TABLE 3 EVA in ink Viscosity @ Viscosity @ (percent by 1 s⁻¹ 100 s⁻¹ Ink# EVA wax weight) (cP) (cP) Example 2 A-C ® 400A 3 14.33 14.09 Example 3A-C ® 405T 3 14.17 14.07 Example 4 A-C ® 400A 4.5 16.46 16.26 Example 5A-C ® 405T 4.5 16.03 15.67 Example 6 A-C ® 400A 5 15.83 15.55 Example 9A-C ® 405T 5 11.94 11.95

All of the inks were filterable and had good Newtonian quality. All ofthe inks were jetted using a Xerox® Phaser® 8860 printer, and displayedexcellent jetting characteristics. The inks did not show any settlingafter standing undisturbed in an oven at 120° C. for a period of 1 week.

Image Characterization and Analysis.

Ink Printing.

Printed images tested for robustness using the standard 3 finger solidink gouge tester and the Duplo paper folder performing a trifold.Printed image was standard IQAF tape-fold-scratch print done at a525×450 dpi resolution.

Procedure.

The scratch/gouge fixture is used to evaluate print robustness toscratch and gouge using the automated Image Quality Analysis Facility(IQAF). Heavy, Medium and Light scratch fingers with specific weightsare applied to the page with a controlled normal force and the printplaten is moved underneath at a constant rate of motion. The prints areevaluated by IQAF for the visibility of the scratch and amount ofmaterial removed.

The scratched print is then fed through a Duplo D-590 folder to performa trifold. The crease area is straightened out over a 90 degree edge andbrushed to remove loose material. The fold crease area is evaluatedusing the image quality analysis facility (IQAF).

Results.

In FIG. 1 and FIG. 2, the fold and scratch results are compared betweenpigmented cyan solid ink containing no ethylene vinyl acetate andpigmented cyan solid ink with incorporation of respectively 3%, 4.5%,and 5% ethylene vinyl acetate containing 13% vinyl acetate (Examples 2,4, and 6). The results indicate that the addition of 3 to 5% by weightethylene vinyl acetate (containing about 13% by weight vinyl acetate)improves the performance of the pigmented solid ink with respect toheavy scratch and especially medium scratch. Further, ethylene vinylacetate incorporation into pigmented solid in has a positive influenceon the ink image robustness with respect to fold. For example, pigmentedcyan ink print scratches almost 4 times less by incorporation of 5% byweight modified ethylene vinyl acetate containing about 13% by weightvinyl acetate.

Addition of ethylene vinyl acetate containing about 13% vinyl acetate byweight to pigmented solid ink significantly improves the performance ofthe ink with respect to scratch and fold. Incorporation of ethylenevinyl acetate with 6% vinyl acetate by weight into pigmented solid inkprovides only a minimal improvement to the scratch and fold propertiesof the ink, especially if the ethylene vinyl acetate wax is present inthe ink at levels greater than 3 percent by weight. FIG. 3 and FIG. 4illustrate scratch and fold results for ink Examples 1, 3 and 5.

Incorporation of ethylene vinyl acetate to dye-based solid ink resultedin similar behavior as with the addition of ethylene vinyl acetate withdifferent levels of vinyl acetate into pigmented solid ink. Results showthat the addition of 1.5% ethylene vinyl acetate by weight containingabout 13% vinyl acetate by weight to pigmented solid ink significantlyimproves the performance of the ink with respect to scratch and fold,while the addition of 5% ethylene vinyl acetate by weight containing 6%vinyl acetate by weight does not provide the same improvement to imagerobustness. FIG. 5 and FIG. 6 illustrate scratch and fold results forComparative Example 7 and dye-based ink Examples 8 and 9.

In embodiments, addition of up to about 5 percent ethylene vinyl acetateby weight containing high levels of vinyl acetate to pigmented anddye-based solid ink significantly improves the performance of the inkwith respect to scratch and fold resistance while preserving the neededcharacteristics of current pigmented solid inks including Newtonianrheology, good filtration properties, thermal stability, ink jettingrobustness, and ink image transfix robustness.

It will be appreciated that various of the above-disclosed and otherfeatures and functions, or alternatives thereof, may be desirablycombined into many other different systems or applications. Also thatvarious presently unforeseen or unanticipated alternatives,modifications, variations or improvements therein may be subsequentlymade by those skilled in the art which are also intended to beencompassed by the following claims. Unless specifically recited in aclaim, steps or components of claims should not be implied or importedfrom the specification or any other claims as to any particular order,number, position, size, shape, angle, color, or material.

1. A phase change ink composition comprising: an ink vehicle; anoptional colorant; and ethylene vinyl acetate in an amount of from about0.1 to about 10 percent by weight based on the total weight of the phasechange ink composition.
 2. The phase change ink composition of claim 1,wherein the ethylene vinyl acetate is present in an amount of from about0.5 percent to about 5 percent by weight based on the total weight ofthe phase change ink composition.
 3. The phase change ink composition ofclaim 1, wherein the ethylene vinyl acetate is present in an amount offrom about 1.5 percent to about 5 percent by weight based on the totalweight of the phase change ink composition.
 4. The phase change inkcomposition of claim 1, wherein the ethylene vinyl acetate is present inan amount of from about 3 percent to about 5 percent by weight based onthe total weight of the phase change ink composition.
 5. The phasechange ink composition of claim 1, wherein the ethylene vinyl acetatehas a molecular weight average of from about 30,000 to about 150,000Daltons.
 6. The phase change ink composition of claim 1, wherein theethylene vinyl acetate has a melting point of from about 45 to about120° C.
 7. The phase change ink composition of claim 1, wherein theethylene vinyl acetate has a freezing point of from about 25 to about100° C.
 8. The phase change ink composition of claim 1, wherein theethylene vinyl acetate has a viscosity of from about 150 to about 2,000cps.
 9. The phase change ink composition of claim 1, wherein theethylene vinyl acetate has a vinyl acetate content of from about 1percent to about 40 percent by weight based on the total weight of theethylene vinyl acetate.
 10. The phase change ink composition of claim 1,wherein the ethylene vinyl acetate is present in an amount of about 0.5percent to about 5 percent and wherein the ethylene vinyl acetate has avinyl acetate content of 5 to about 13 percent by weight based on thetotal weight of the ethylene vinyl acetate.
 11. The phase change inkcomposition of claim 1, wherein the ethylene vinyl acetate is present inan amount of from about 5 percent by weight based on the total weight ofthe phase change ink composition; and wherein the ethylene vinyl acetatehas a vinyl acetate content of about 25 to about 30 percent vinylacetate based on the total weight of the ethylene vinyl acetate.
 12. Thephase change ink composition of claim 1, wherein the colorant is a dye;or wherein the colorant is a pigment.
 13. The phase change inkcomposition of claim 1, wherein the ink vehicle comprises a wax.
 14. Thephase change ink composition of claim 1, wherein the ink vehiclecomprises a polymethylene wax, a polyethylene wax, a biodegradable andcompostable wax, a biodegradable and compostable polyethylene wax, or amixture or combination thereof.
 15. The phase change ink composition ofclaim 1, wherein the ink vehicle is present in the phase change inkcomposition in an amount of from about 25 percent to about 65 percent byweight based on the total weight of the phase change ink composition.16. The phase change ink composition of claim 1, wherein the ink vehiclecomprises a monoamide, a triamide, or a mixture thereof.
 17. The phasechange ink composition of claim 1, wherein the ink vehicle comprises (a)stearyl stearamide, (b) a triamide, or (c) mixtures thereof.
 18. Thephase change ink composition of claim 1, wherein the ink vehiclecomprises an isocyanate-derived material, a urethane isocyanate-derivedmaterial, a urea isocyanate-derived material, a urethane/ureaisocyanate-derived material, or mixtures thereof; or wherein the inkvehicle comprises a mixture of one or more amides and one or moreisocyanate-derived materials.
 19. A method comprising: incorporatinginto an ink jet printing apparatus a phase change ink compositioncomprising an ink vehicle; an optional colorant; and ethylene vinylacetate in an amount of from about 0.1 to about 10 percent by weightbased on the total weight of the phase change ink composition; meltingthe ink composition; and causing droplets of the melted ink to beejected in an imagewise pattern onto a substrate.
 20. An ink jet printerstick or pellet containing a phase change ink composition comprising: anink vehicle; an optional colorant; and ethylene vinyl acetate in anamount of from about 0.1 to about 10 percent by weight based on thetotal weight of the phase change ink composition.